Hair extension



FIG. 1 is a front elevation view of a hair extension showing my new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a perspective view thereof;

FIG. 6 is a perspective view of a fastener of the hair extension, shown separately to show aspects of the design that are not visible when combined;

FIG. 7 is a top plan view thereof;

FIG. 8 is a bottom plan view thereof; and,

FIG. 9 is an elevation view thereof. 

CLAIM The ornamental design for a hair extension, as shown and described. 